1. Field of the Invention
This invention relates to a power transmission system for vehicles, mainly for motorcycles.
2. Description of the Prior Art
In general, a power transmission system for vehicles experiences vibration when it receives an excessively large back load due to sudden deceleration of the vehicle. For minimizing such vibration, there has been proposed a power transmission system which is provided with a damper formed of an elastic material such as rubber. However, in this known power transmission system, it is necessary to make the capacity of the elastic element sufficiently high. This causes an increase in the dimensions not only of the damper but also of the power transmission system as a whole. Moreover, the above-mentioned damper responds to load both in the forward and reverse directions, so that it causes an increase in vibration of the power transmission system when the load is varied.